5 - CONCLUSIONS
If further studies support the concept, the eventual usefulness of the VIT Trapezoid in understanding the water
dynamics of an agricultural field is quite apparent. It will be necessary to validate the assumptions made in the
trapezoid’s development, and make modifications as necessary. As the goal of the authors is to ultimately see
the application of these results toward farm irrigation management, it may be necessary to reduce inputs even
more to make the applications practical. Sensitivity tests of the various input parameters should therefore be
performed to see if any can be e limina ted or replaced by constants.
Figure 5. Subsample of SAVI-fT.-TJ pairs (+) acquired with digital cameras and a thermal scanner over a
cotton field. A linear regression through these points results in canopy and bare soil temperature estimates (_)
that agree fairly well with coincident ground measurements (a).
6 - ACKNOWLEDGEMENTS
The authors would like to acknowledge the many people at die USDA-ARS U.S. Water Conservation
Laboratory, Phoenix, Ariz., who participated in the design and implementation of the alfalfa experiment and
the arduous data acquisition and archiving processes, particularly Ray Jackson, Paul Pinter, Stephanie Johnson,
and Ron Seay. Denis Troufleau (CEMAGREF/ENGREF, Montpellier, FRANCE) was instrumental in the
concept development based on a two-component simulation model.
7 - REFERENCES
Brutsaert, W.H. (1982) Evaporation into the Atmosphere . D. Reidel Publ. Co., London, England, 299 p.
Clothier, B.E., K.L. Clawson, P.J. Pinter, Jr., M.S. Moran, R.J. Reginato and R.D. Jackson (1986)
Estimation of soil heat flux from net radiation during the growth of alfalfa, Aerie, and For. Meteorol.
37:319-329.
Daughtry, C.S.T., W.P. Kustas, M.S. Moran, P.J. Pinter, Jr., R.D. Jackson, P.W. Brown, W.D. Nichols and
L.W. Gay (1990) Spectral estimates of net radiation and soil heat flux, Remote Sens. Environ. 32:111-124.
Heilman, J.L., W.E. Heilman and D.G. Moore (1981) Remote sensing of canopy temperature at incomplete
cover, Agronomy Journal 73:403-406.
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